MPOrderedEnvir : OrderedEnvir{

	var <>size = 0;

	put{ arg key, obj;
		super.put(key, obj);
		size = size + 1;
	}
	
	removeAt{ arg key;
		super.removeAt(key);
		if(size > 0){
			size = size -1;
		};
	}
	
}